I have transported kayaks (scrambler, chinook) on roofs of small honda (prelude), medium Honda (CRV) to large honda currently (Oddessy) and I always do the same thing. Turn the kayak upside down, then using two lengths of nylon cord I run a length across the front and back using either the roof rack large car or gutter hooks small car. I pull the cords tight because I double back to where I started and I am off and away. I have never had a problem over hundreds of trips. I do not even use front and back ropes (to the bumpers) most of the time. I am good with knots. I walk my kayak to the water, they are not that heavy compared to my canoe. Less is more.